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MG MGB Technical - Cylinder marks

Hi All

I have taken the head off and started to stip and inspect the engine to try to get an idea of its condition. The cylinder bores do not have a lip so hopefully not too much wear since it was last rebuilt.( I dont know its history other than it is a goldseal which may have been rebuilt since the original goldseal rebuild). Cylinder 3 has a scorch type mark on both the left and right sides, see pic. What would cause this is it something to be overly concerned about?

Tony Brough

If those marks are blue/purple, on steel that indicates in excess of 280 degC. I think Gold Seals were fitted with liners. Is there a corresponding hot spot on 2 or 4?
Allan Reeling

There appears to be a liner. Look at 6 oclock and you will see what appears to be a liner mark.
Sandy
Sanders

Thanks for the replys. I will hopefully get chance to have another look tomorrow but I dont remember see it in any of the other cylinders.

Was lining of the cylinders a successful repair or did it bring its own problems?

Tony
Tony Brough

Putting a liner in returned the bores to original diameter which allowed the use of stock pistons and rings at the factory, a boring machine set up to a standard size and obviated the possible dangers of over boring. Putting a liner in is an excellent "repair".
Allan Reeling

Thanks Allan

I have had another look and the marks are only in number 3. They do not appear to be blue or purple, more of a darker grey.

I have just done a drip down test as per John Twist. No 3 drained away quite quickly in comparison to the others so I am planning to take the pistons out to examine the piston rings as sell as the condition of the bearings.
Tony Brough

18V engine block production shifted to Qualcast in Leeds around 1971, there were problems with porosities on a lot of blocks. Rather than throw them away BL turned them into Goldseal units by fitting liners. A bargain giving a customer a new block not reconditioned!
Peter
Peter Burgess Tuning

Peter, Is that the same Qualcast as in Qualcast Lawn mowers?
Allan Reeling

I think so :) We had a customer many years ago who did the boring on the new blocks and he spilled the beans (pun intended).
Peter
Peter Burgess Tuning

Not so "QUALity CASTing then!!
Allan Reeling

This thread was discussed between 26/08/2017 and 29/08/2017

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